I am very new to realflow and I will like to fill a beer bottle I modelled and animated in maya with realflow particles. The problem is I need a way to fill the bottle before the bottle starts moving when I hit simulate.

The answer to your question is to make use of the locking of the timeline while you are filling the bottle. Once the bottle is full with particles, stop the simulation, then you can store the current state as initial state and un-lock the timeline, then restart the simulation. The icon for locking/unlocking is down left, the lock icon. for example this video on youtubehttps://youtu.be/5LZBpuL07M8